Fixes incorrect link to Bower homepage.
Fixing minor typo
made link to Joomla extensions generic

Since there is no generic plugin we can suggest at this point (only two plugins, one commercial, one for a Joomla mod)
fixed typo in link
Small tweak to SVG.rst documentation file

This seems to have been a copy-paste legacy from the HTML-CSS documentation, speaking of a dash (the one in HTML-CSS) that isn't present in the identifier SVG.